SPRING 2009 Nuclear Physics Seminar Schedule
(Course Number P599-002)

 

PLEASE NOTE START TIME

Unless otherwise noted, the nuclear physics seminars are held on Mondays, at 2:20 p.m. in Room 307 of UTK's Nielsen Physics Building. Abstracts are included below the schedule. NOTE The first seminar of each month is intended to be of interest to both the Nuclear Physics and the Condensed Matter communities and will be held in Nielsen Room 306.

The UTK Physics Colloquium Schedule and ORNL Physics Division Seminar Schedule might also be of interest.

Dr. Kate Jones is chair of the seminar program. She may be contacted via e-mail at: kgrzywac@utk.edu  

 

Date

Speaker

Title

January 19

Martin Luther King day - no seminar

NONE

January 26

Milan Matos (LSU)
matos@lsu.edu

Time-of-flight magnetic-rigidity mass measurements and their importance for nuclear astrophysics

February 2

Thomas Papenbrock In 306
tpapenbr@utk.edu

Nuclear energy density functional theory CANCELLED

February 9

Yang Sun (Shanghai)

Recent projected shell model study on nuclear structure

February 16

Catalin Matei (ORAU)
mateic@ornl.gov

Measurements and R-Matrix analysis of the 12C(a,g)16O reaction

February 23

JUSTIPEN WORKSHOP at ORNL

NONE

March 2

Ren Cooper (ORNL)
cooperrj@ornl.gov

Gamma-ray Imagaing with Segmented Semiconductor Detectors

March 9

Thomas Papenbrock In 306
tpapenbr@
utk.edu

Nuclear Energy Density Funtional Theory

March 16

SPRING BREAK

NONE

March 23

Libby McCutchan (ANL)
mccutchan@phy.anl.gov

Testing ab-initio calculations in A=10 nuclei through precision lifetime measurements

March 30

A. Eguiluz In 306

Density-Functional theory, and its Time-Dependent Extension, in Condensed-Matter Physics

April 6

Irakli Garishvili
irakli.garishvili@gmail.com

Open Heavy Flavor Measurements in PHENIX

April 13

Nick Stone

The Physics of Cu Nuclei – with particular reference to magnetic dipole moments – from A = 56 to A = 78.

April 20

Felix Liang (ORNL)
liangjf@ornl.gov

Studying dynamic polarization in the two-body breakup of 17F


Abstracts

January 26

M.Matos

TOF-BR mass measurements and their importance for nuclear astrophysics

Atomic masses play an important role in the field of nuclear physics and astrophysics. The lack of experimental values for exotic nuclides has triggered a rapid development of new mass measurement devices around the world, including Time-of-Flight (TOF) mass measurements. The TOF technique, with access to the most exotic nuclides (minimum rate requirement of the order of 0.01 particles/s and a measurement time shorter than ~1ms), is a complementary method to the very precise but more limited Penning trap mass measurements.
The TOF-Br technique that includes a position measurement for magnetic rigidity correction has been implemented at the NSCL facility using the A1900 separator and the S800 spectrograph.
The first experiment, focused on the neutron rich isotopes in the region of Z ~ 20-30, important for r‑process calculations as well as for calculations of processes occurring in the crust of accreting neutron stars, has been successfully performed. An experiment with a similar TOF-Br technique in the N=Z area is approved and planned by the same collaboration at the next generation radioactive beam facility RIBF at RIKEN. The BigRIPS separator and the zero degree spectrometer will be used to provide the cocktail beam of interest and the magnetic rigidity correction.

Details of both techniques, together with preliminary results from the first NSCL experiment, will be presented. The impact on nuclear structure and astrophysics as well as future plans will be discussed.

 


February 2

T Papenbrock

Nuclear energy density functional theory

Nuclear energy-density functionals are used to compute the properties of atomic nuclei across the nuclear chart. The construction and constraining of the functional is a challenging task and focus of contemporary research in nuclear theory. In the limit of dilute neutron matter, the functional becomes universal and applies to a variety of different physical systems ranging from neutron gases to ultracold atom gases.

 


February 9

Yang Sun

Recent Projected-Shell-Model Study on Nuclear Structure
Deformed single particle states (e.g. those generated by the Nilsson Model) form a good starting basis for deformed nuclei. Broken rotational symmetry in the Nilsson states can be recovered by angular momentum projection. If configurations are built with the projected deformed basis, shell model configuration mixing is carried out when a two-body Hamiltonian is diagonalized in this basis. This is the basic idea of the Projected Shell Model.

Choice of the configurations corresponds to the shell model truncation. This gives flexibility to study collective as well as single particle excitations in deformed nuclei. For thecollective motions, rotational states, and beta-, gamma-, and scissors vibrational states, can be studied. Projected multi-quasiparticle configurations form good bases for single-particle excitations. For well deformed nuclei, each projected configuration corresponds to a rotational band. Diagonalization introduces mixing among these bands, which describes K-mixing.

In this talk, I will report on the recent study by the Projected Shell Model, with examples for the structure of transfermium nuclei in the Z=100 mass region.





February 16

C. Matei

Measurements and R-Matrix analysis of the 12C(a,g)16O reaction

The 12C(a,g)16O radiative capture reaction is one of the most important reactions in nuclear astrophysics as its reaction rate strongly effects the present C to O ratio in the Universe. Recent experiments at DRAGON, TRIUMFand Ohio University offer new information on cascade and ground state transitions in 16O. Transitions through the 6.05- and 6.92-MeV levels in 16O are analyzed in the R-matrix formalism. An overview of the 12C(a,g)16O reaction, details of the analysis and updated S-factors will be presented.
 


March 2

R. Cooper

Gamma-ray Imaging with Segmented Semiconductor Detectors

The field of gamma-ray imaging has recently experienced a resurgence with new applications emerging along with renewed interest in those which already exist.  The fine position and energy resolution afforded by semiconductor gamma-ray detectors may make them ideal candidates for imaging applications in fields such as  medicine, security, nuclear decommissioning and environmental monitoring.

The development and characterization of HPGe and CZT detectors for gamma-ray imaging will be presented.


March 9

T.Papenbrock

Nuclear energy density functional theory

Nuclear energy-density functionals are used to compute the properties of atomic nuclei across the nuclear chart. The construction and constraining of the functional is a challenging task and focus of contemporary research in nuclear theory. In the limit of dilute neutron matter, the functional becomes universal and applies to a variety of different physical systems ranging from neutron gases to ultracold atom gases.  


March 23

E. McCutchan

Testing ab-inito calculations in A=10 nuclei through precision lifetime measurements

A new generation of calculations of light nuclei has deepened our understanding of how nuclides are bound, the structure of their wavefunctions, and the importance of 3-body forces.  In the A = 10 systems, the inclusion of 3-body forces inverts the sequence of low-lying states, which has been explained by the important contribution of the 3-body interaction to the overall spin orbit force.  Precise experimental measurements are now necessary to help constrain models of the 3-body forces.  In this work, we focus on inferring lifetimes through the slowing of nuclei in materials, the DSAM (Doppler Shift Attenuation Method) and improving the accuracy to a level (<5%) where the electromagnetic matrix elements between excited states can provide useful constraints on modern calculations.  An improved DSAM technique will be discussed which includes careful selection of the kinematic conditions for producing the states of interest, control of feeding from higher levels, improvements in gamma-ray detection, and better knowledge of how ions stop in materials.  Each are important for moving beyond the original >25% measurements from the 1960’s and improving both precision and accuracy.   Results of experiments on 10Be and 10C will be presented and discussed in terms of recent ab-initio calculations.  This research is supported by the DOE Office of Nuclear Physics under contract DE-AC02-06CH11357.  

 

 


March 30

A. Eguiluz

Density-Functional theory, and its Time-Dependent Extension, in Condensed-Matter Physics

A bird’s eye view will be presented of density-functional theory (DFT), including second and third generation methods, as they are used in condensed-matter physics. The omnipresent local- density approximation (LDA) will be introduced, and its inadequacy for the treatment of strongly-correlated materials will be highlighted. A physically-motivated “orbital functional,” which goes beyond the LDA non-perturbatively, the so-called LDA+U method, will be introduced.  The time-dependent DFT (TDDFT) method, which is designed to study the excited states of the many-body Fermion Hamiltonian, will be introduced.  As an example, the interplay between the low-energy electronic excitations and the metal-insulator transition in V2O3 will be discussed, and framed vs. (brand new) inelastic x-ray scattering experiments carried out at the ESRF in Grenoble.

 


April 6

Irakli Garishvili

Open Heavy Flavor Measurements in PHENIX

Produced during the early stages of relativistic heavy ion collisions, heavy flavor quarks
serve as an extremely important probe of QGP, the strongly interacting medium believed to
be produced in these collisions. As a consequence measuring observables like elliptic flow
and the nuclear modification factor is of great importance.

Open heavy flavor production in p+p collisions is an absolutely necessary baseline
measurement for nuclear modification factor. It also provides a good cross-check of pQCD
calculations.

Non-photonic single leptons are used to tag the production of heavy flavor quarks via
semileptonic decay of heavy flavor mesons (D,B). PHENIX has a unique ability to measure
single lepton spectra both at pseudorapidity |eta|<0.35 and at 1.4<|eta|<1.9 with its
Central and Muon arms, respectively. In both cases this is done via background subtraction
(Dalitz decays and photon conversions in the case of electrons and light hadron decays and
misidentification in the case of muons) from raw spectra of lepton candidate tracks. In
addition, PHENIX central arms have an ability to measure the charm/bottom ratio in
non-photonic electron production by studying electron-hadron correlations.

The most recent PHENIX single lepton results will be presented and compared to the available
theoretical model predictions.


April 13

N. Stone

The Physics of Cu Nuclei – with particular reference to magnetic dipole moments – from A = 56 to A = 78.

Copper isotopes, with a single proton outside the closed shell at Z = 28, form an attractive laboratory for testing the best nuclear models. The magnetic dipole moment provides such a test and recent years have seen a string of magnetic moments measured, extending from N = 28, through N = 40 and approaching N = 50. This seminar will outline the physics of nuclear magnetism and briefly describe the variety of methods which have been used to obtain the results. Their interpretation, and the assistance they give to establishing a reliable nuclear model to describe inaccessible nuclei in the region of the R-process waiting point at 78Ni will be discussed.


April 20

Felix Liang

Studying dynamic polarization in the two-body breakup of 17F

Coulomb dissociation is an important tool for studying radiative capture
reactions in nuclear astrophysics when direct measurements are difficult or
impossible, such as those involving short-lived radioactive nuclei[1].
It is important to understand the breakup processes in order to correctly
extract relevant information. For loosely bound proton-rich
nuclei, first order perturbation theory calculations are not
reliable and the inclusion of higher order effects is necessary.
Of particular importance
is the dynamic polarization effect where the valence proton is displaced
behind the core nucleus and shielded from the target. This
effect is proportional to the cube of the target charge, Z^3. It
manifests in the reduction of the breakup probability as compared to first
order perturbation theory, and the reduction in breakup probability is
expected to be smaller for targets of lower Z[2].

We have measured the breakup of 17^F by bombarding 58^Ni and
208^Pb targets. The radioactive 17^F was produced by an ISOL method
and post-accelerated to an energy of 10 MeV/nucleon. The angular
distribution of coincident oxygen and proton for 17^F on 208^Pb shows
a larger reduction of breakup probability with respect to first order
perturbation theory than that for the 58^Ni target. Comparisons with
dynamical calculations which take into account the Z^3 correction to
study the dynamic polarization in the breakup of 17^F will be presented.

[1] G. Baur, C. A. Bertulani, H. Rebel, Nucl. Phys. A 458(1986)188.
[2] H. Esbensen, G. F. Bertsch, Nucl. Phys. A 706(2002)383.








Previous Nuclear Physics Seminars

·      Spring 2006

·      Fall 2006

·      Spring 2007

·      Fall 2007